Portable bathtub



FIG. 1 is a top plan view of a portable bathtub showing my new design;

FIG. 2 is a cross-sectional view taken on line 2--2 of FIG. 1;

FIG. 3 is a cross-sectional view taken on line 3--3 of FIG. 1, and,

FIG. 4 is a rear elevational view thereof. 

The ornamental design for a portable bathtub, as shown in the accompanying drawing. 